A number of studies present cross sections of the Cape Fear interval that include geophysical logs (gamma ray, spontaneous potential) (Colquhoun and others, 1983; Aucott and others, 1987; Temples and Waddell, 1996). These logs are a source of semiquantitative estimates of percent shale in the Cape Fear interval. Brown and others (1979) provided actual percentages for the Cape Fear interval (their Unit E), but these estimates are from wells in Georgia. Gohn and others (1977) presented results of textural and mineralogical analysis of the Cape Fear Formation conducted on samples from a well near Charleston. Their analyses indicate that the Cape Fear interval is primarily silt and that shale composes between 20 and 40 percent of the unit. For the GIS, we combined the analysis of Gohn and others (1977; their fig. 3) and Brown and others (1979). These shale percentages generally agree with the estimates derived from the geophysical logs.